Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.1.1 (hexokinase)
 5,274 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The relative mobilities of six enzymes from the trophozoites of five axenically-cultured isolates of Giardia from human, cat, and guinea pig hosts were compared by starch and polyacrylamide gel electrophoresis. The six enzymes compared were malate dehydrogenase (NAD+) (MDH) (EC 1.1.1.37), malate dehydrogenase (decarboxylating) (ME) (EC 1.1.1.40), hexokinase (EC 2.7.1.1), 6-phosphogluconate dehydrogenase (EC 1.1.1.44), glucose-6-phosphate dehydrogenase (G6P) (EC 1.1.1.49), and alpha-glycerophosphate dehydrogenase (EC 1.1.1.8). The latter three enzymes have not been previously reported in Giardia. On the basis of zymogram patterns, the five Giardia isolates were divided into three zymodemes. Zymodeme I comprised human-1/England, human-1/Bethesda, and cat-1/Portland, Zymodeme II the guinea pig-1/Portland isolate, and Zymodeme III the human-1/Portland isolate. These zymodemes were further substantiated when several physical and kinetic properties of three of the enzymes, MDH, ME, and G6P, were examined. Our results, in which Giardia isolated from different mammalian hosts share multiple isoenzymes, question the validity of the practice of assigning Giardia species names on the basis of the animal host from which the protozoan was obtained.
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PMID:A comparison of isozymes of five axenic Giardia isolates. 667 61

The activity of NAD-linked alpha-glycerol-3-phosphate dehydrogenase (NAD-G3PDH; EC 1.1.1.8) was depressed by 35% when the thyroid hormone 3,3',5-triiodo-L-thyronine (20 micrograms/liter) was added to the serum-free, hormonally supplemented medium of cultured neonatal rat heart cells. The degree of depression was greater (65%) when the medium contained normal serum levels of hydrocortisone and insulin. There is a dramatic inverse dose-response relationship between triiodothyronine levels and NAD-G3PDH activity. The classic elevation by thyroid hormones of the FAD-linked alpha-glycerol-3-phosphate dehydrogenase (FAD-G3PD; EC 1.1.99.5) was observed concurrently. The medium-glucose depletion rate in triiodothyronine-free cells was depressed 32% through 11 days-in-culture, indicating reduced glycolytic activity. The activities of nine other metabolically important enzymes which were measured during this study, including hexokinase, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, phosphofructokinase, pyruvate kinase, malate dehydrogenase, NAD-isocitrate dehydrogenase, NADH cytochrome c reductase, and succinic cytochrome c reductase, did not respond to varying triiodothyronine concentrations.
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PMID:Triiodothyronine depresses the NAD-linked glycerol-3-phosphate dehydrogenase activity of cultured neonatal rat heart cells. 669 42

The pathways for catabolism of fructose were investigated in the type strains of Azospirillum lipoferum and Azospirillum brasilense grown aerobically with (NH4)2SO4 as the nitrogen source. When grown on fructose, the former species possessed a complete Entner-Doudoroff pathway, whereas the latter species lacked activity for glucose-6-phosphate dehydrogenase. Both species possessed a complete catabolic Embden-Meyerhof-Parnas pathway. Neither species possessed the key enzyme of the hexose monophosphate pathway, 6-phosphogluconate dehydrogenase. Both species could phosphorylate fructose to fructose-1-phosphate by means of a phosphoenolpyruvate-phosphotransferase system, and high activities of 1-phosphofructokinase occurred. Both species possessed glucokinase activity, but only A. lipoferum had hexokinase activity; moreover, the cells of A. brasilense were nearly impermeable to glucose, accounting for the inability of this species to grow on glucose. Both species possessed pyruvate dehydrogenase, a complete tricarboxylic acid cycle, a glyoxylate shunt, and malic enzyme. Analysis of the acidic end products for both species indicated the formation of only small amounts of various organic acids, and most of the titratable acidity was due to utilization of the ammonium ions of the medium. Gluconic acid was not formed during growth of either species on fructose but was detected during growth of A. lipoferum on glucose; this species also possessed an NADP-linked glucose dehydrogenase and gluconokinase.
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PMID:Fructose catabolism in Azospirillum brasilense and Azospirillum lipoferum. 673 86

A serum-free, hormone-supplemented medium (SFHM) for maintaining neonatal rat heart cells in culture has been developed in this laboratory (Mohamed et al., 1983). Morphological assessment of heart cells grown in SFHM show it to be similar to commonly used serum-supplemented media. To quantitatively compare cell behavior in SFHM with serum-supplemented media, the activities of ten regulatory enzymes which represent four metabolic pathways were studied in heart cells cultured in SFHM. The enzyme activities which were measured included hexokinase, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, phosphofructokinase, pyruvate kinase, NAD+-linked sn-glycerol-3-phosphate dehydrogenase, malate dehydrogenase, NAD+-linked isocitrate dehydrogenase, NADH-cytochrome c reductase, and succinic cytochrome c reductase. Rat heart cells maintained in culture on SFHM are not only qualitatively and quantitatively similar to those maintained in serum-supplemented medium but also provide a more suitable model system for metabolic studies of neonatal cardiac tissue for several reasons: 1) many enzyme activities that may represent dedifferentiation are elevated by serum; 2) NAD-linked glycerol-3-phosphate dehydrogenase activity in cells maintained on SFHM is similar to the in vivo activity; 3) cells beat at or near the in vivo frequency and can be maintained 3 months on SFHM; 4) the SFHM is chemically defined and thus can be completely manipulated by the investigator. The effects of three concentrations of hydrocortisone (HC) (5,000 ng/ml, 50 micrograms/ml, 0 ng/ml) on heart cells cultured in SFHM supported our previous conclusion that function (beating) and growth (protein accumulation) are inversely related in cultured neonatal rat heart cells.
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PMID:Control of enzyme activity levels by serum and hydrocortisone in neonatal rat heart cells cultured in serum-free medium. 674 46

In 11 patients on CAPD with persisting anemia the survival of red cells labelled with 51Cr, red cell mass and the levels of several enzymes within red cells were measured. 51Cr red cell survival was shortened in 9/11 (mean +/- SD:20.0 +/- 4.9 days) and correlated with red cell mass, i.e. with the degree of anemia (r = 0.79, P less than 0.01). Determinations of the levels of enzymes of the hexose monophosphate shunt and the glycolytic pathway revealed no obvious defects in red cell metabolism. The level of hexokinase (HK) was normal whereas the activities of glucose-6-phosphate dehydrogenase (G-6-PD), 6-phosphogluconate dehydrogenase (6-PGD), glutathione reductase (GR) and pyruvate kinase (PK) as well as reduced glutathione (GSH) were increased significantly. CAPD did not eliminate the hemolytic component of anemia in the majority of these patients.
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PMID:Red cell survival and red cell enzymes in patients on continuous peritoneal dialysis (CAPD). 685 Dec 63

Protease B [EC 3.4.22.9] was purified from baker's yeast by plasmolysis of yeast, acid activation, acid precipitation, and column chromatographies on QAE-Sephadex, SP-Sephadex, D-tryptophan methyl ester-Sepharose 4B and Sephadex G-100. The purified enzyme was inhibited by phenylmethylsulfonyl fluoride and sulfhydryl-blocking reagents. Chymostatin and antipain at extremely low concentrations (1 micro M) inhibited the protease B. The effects of the enzyme on various yeast enzymes were examined by measuring their inactivation. The enzyme inactivated 6-phosphogluconate dehydrogenase [EC 1.1.1.44] and uricase [EC 1.7.3.3], but not malate dehydrogenase [EC 1.1.1.37], alcohol dehydrogenase [EC 1.1.1.1], glutamate dehydrogenase [EC 1.4.1.3], glucose-6-phosphate dehydrogenase [EC 1.1.1.49] or hexokinase [EC 2.7.1.1].
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PMID:Purification and characterization of yeast protease B. 699 57

1. Activities of 20 red cell enzymes were compared in 8 normal female Ovis Aries, in a serially bled ewe followed by 243 days, and in young and old red cell populations separated by density gradient centrifugation. 2. These comparisons indicate that the erythrocyte enzymes which show significant changes with cell age are glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, hexokinase, phosphoglucose isomerase, lactate dehydrogenase, glutathione reductase, enolase and phosphoglycerate kinase. 3. The usefulness of these data in interpretation of enzyme activities from fetal Ovis Aries is discussed.
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PMID:Erythrocyte enzymes in Ovis aries. Effect of cell age. 706 Mar 50

Kinetics and thermodynamics of the spontaneous formation of glucose-6-arsenate (G6As) and 6-arsenogluconate (6AsG) as well as the ability of these compounds for substituting their phosphorylated homologues in enzymic reactions have been studied. Formation of G6As and glucose-6-phosphate (G6P) shows similar thermodynamic constants. Both reactions are endothermic, endergonic, and occur with a decrease of entropy. However, the kinetic coefficients of the spontaneous formation of the arsenate esters are ca. 10(5) times greater than those of their homologous phosphate esters. The activation energy of the spontaneous formation of G6As (E = +12 kcal mol-1) is even smaller than that of the formation of G6P by alkaline phosphatase (E = +13 kcal mol-1). Similar to the case of monoalkylphosphates, the monoanion species of G6As is much more reactive than the dianion species. This is an important difference with respect to G6P. Arsenate esters are good analogs of the phosphate esters for a variety of enzymes. Glucose-6-phosphate dehydrogenase shows nearly similar values of Km and Vmax for either G6P or G6As, and hexokinase is similarly inhibited by both compounds. 6-phosphogluconate dehydrogenase has the same Vmax with respect to 6PG and 6AsG, although the enzyme shows a much lower affinity for the latter substrate. The calculated half-lives at 25 degrees C and pH 7 of G6As and 6AsG are only ca, 6 and 30 min respectively, they increase at lower temperature and alkaline pH. At 0 degrees C and pH 9 the half-life of G6As is ca. 20 h.
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PMID:[Formation and properties of sugar arsenate esters]. 714 95

Two major hexokinases (ATP: D-hexose 6-phosphotransferases, EC 2.7.1.1) have been identified in tissues of Homarus americanus (lobster) and separated from each other by DEAE-cellulose ion-exchange chromatography and by polyacrylamide gel electrophoresis. The molecular weight of each, determined by gel filtration, is about 50 000. Hexokinase II, named for its column elution order, resembles hexokinase isozymes I and II of vertebrates. Km values for glucose, mannose and fructose are 0.08, 0.13 and 6.7 mM, respectively. It is strongly inhibited by the reaction products, ADP and glucose-6-P (Ki = 0.8 mM). Hexokinase I appears to be different from any animal hexokinase previously described. It has a high affinity for mannose and fructose and low affinity for glucose. Km values are 6, 0.07 and 1.2 mM and relative maximum rates 100, 520 and 1070 for glucose, mannose and fructose, respectively. Hexokinase I is not inhibited by physiological concentrations of ATP nor by glucose-6-P , mannose-6-P or fructose-6-P even at high concentrations. Both enzymes occur in muscle at about 10% of the concentration found in the hepatopancreas. The use of Leuconostoc mesenteroides glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate: NADP+ 1-oxidoreductase, EC 1.1.1.49), with NAD as cofactor, is recommended for measuring hexokinases in crude tissue preparations to avoid the variable further reduction of nucleotide caused by the action of 6-phosphogluconate dehydrogenase when NADP is used with yeast glucose-6-phosphate dehydrogenase.
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PMID:Two hexokinases of Homarus americanus (lobster), one having great affinity for mannose and fructose and low affinity for glucose. 721 58

The presence of hexokinase, aldolase, glyceraldehyde-phosphate dehydrogenase, phosphoglycerate kinase, glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase has been detected in Y. enterocolitica, which indicates the glycolytic and pentosophosphate pathways of glucose catabolism. Y. enterocolitica can be classified as an opportunistic anaerobic microorganism on the basis of the whole complex of its characteristics (growth in both aerobic and anaerobic conditions, the reduction of nitrates into nitrites, the presence of higly active glycolytic enzymes).
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PMID:[Glucose metabolism in Yersinia enterocolitica cells]. 743 20


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